A Study on Lipid Removal from Yeast Homogenate by Chemical Pretreatment

Lipids discharged into the yeast homogenate following the cell disruption process have a deleterious impact on the performance of chromatography columns during downstream processing. In this study, the removal of lipids from Pichia pastoris crude extract was investigated using various chemicals at varied concentrations. After treatment of the sample with 0.05 M borax and 1.5% PEI, a lipid reduction of about 52% and 79% was respectively obtained in the flocculated protein. The addition of PEG 6000 to the sample at a final concentration of 20% led to 57% lipid removal. A lipid reduction of 67%–70% was observed when protein precipitation was performed by 20%–40% ammonium sulfate. The efficiency of acetone and diethyl ether for lipid reduction was greater than that of isopropanol, and substantial lipid removal (95%–100%) was demonstrated after feedstock treatment with 0.5%–5% acetone and diethyl ether. After conducting detergent lipid dissolution experiments, it was revealed that non-ionic detergents (Triton X-100 and Tween 20) at a concentration of 0.1% were able to eliminate 100% of lipids in the feedstock. Overall, these findings suggest that such chemical treatment strategies may be considered to be used for pre-treating process streams and facilitating related research and applications in downstream processing.